This invention relates to protecting optical components against an atmosphere containing moving particles and other debris, and more particularly to an optical sensor and profiler which is shielded from the smoke and weld spatter generated by an arc welding process.
The use of optical sensors to guide industrial processes is increasing rapidly. One of the major problems encountered in this trend is maintaining the transmission of those optical elements which form the window through which the sensor views the industrial process. This problem can be substantial even with clean processes because of dust and smoke normally found in the work place. However, when a sensor must observe directly a process producing smoke, spatter or other airborne debris, the problem of window cleanliness can become critical, requiring that the process be stopped frequently to clean or change windows, or that some type of refreshable window mechanism or shutter be installed. Optical sensors used for weld groove tracking and weld quality control are good examples of devices which should tolerate a dirty atmosphere. A reasonable goal is that windows should remain clean at least until some procedure required by the process, such as placing another spool of wire on a MIG (metal inert gas) weld system, or a natural work division such as a change of shift provides a maintenance opportunity Furthermore, maintenance should be inexpensive and easy to implement. The present window and optics protection system meets these goals.
Window protection is used in various optical applications, of which laser machining and medical cutting operations form good general examples. A common protection mode is to flow gas around the optical element facing the exterior of the device, and thence down an elongated channel (see FIG. 1). The drag of the out-flowing gas serves to stop most smoke, particles and other debris from flowing up through the opening and contacting the optical element. However, in the case of most MIG welding operations and other industrial operations such as grinding, particles are driven with substantial speed toward the optics, while light economy requires openings at least several millimeters in diameter. In such cases it was found that sufficient gas flow to stop most of the particles from reaching the optics is either difficult to support or disturbs the process. Thus the approaches used in the prior art to protect optics are either insufficient, inconvenient, or disrupt the process when applied, for instance, to MIG welding.